A mixture of ethane, ethene and ethyne is passed through ammoniacal `AgNO_3` solution. The gases which contain unreacted are

Options

A. Ethane and ethene
B. Ethane and ethyne
C. Ethene and ethyne
D. Ethane only

Explanation

To solve the problem of identifying the unreacted gases when a mixture of ethane (C2H6), ethene (C2H4), and ethyne (C2H2) is passed through ammoniacal AgNO3 solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- Ammoniacal AgNO3 solution is known as Tollens' reagent. It primarily reacts with aldehydes, terminal alkynes, and some aromatic compounds. It does not react with alkenes or alkanes.

2. **Identifying the Compounds**:
- The mixture contains:
- Ethane (C2H6) - an alkane
- Ethene (C2H4) - an alkene
- Ethyne (C2H2) - a terminal alkyne

3. **Analyzing Each Compound**:
- **Ethane (C2H6)**: As an alkane, it does not react with Tollens' reagent. Therefore, it will remain unreacted.
- **Ethene (C2H4)**: As an alkene, it also does not react with Tollens' reagent. Therefore, it will remain unreacted.
- **Ethyne (C2H2)**: As a terminal alkyne, it will react with Tollens' reagent, producing a white precipitate of silver.

4. **Conclusion**:
- After passing the mixture through ammoniacal AgNO3, the gases that remain unreacted are ethane (C2H6) and ethene (C2H4).

### Final Answer:
The gases which remain unreacted are **ethane (C2H6) and ethene (C2H4)**.

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